The present invention relates to a method and apparatus for producing an air textured yarn having a relatively low residual shrinkage.
Methods and apparatus are known from German Patent 32 10 784, in which the yarn to be textured is supplied as a preoriented, thermoplastic yarn. The yarn is drawn in a draw zone and subsequently extended in an air nozzle to form loops, curls, bows and the like. The yarn produced has a residual shrinkage. The above referenced copending application Ser. No. 07/399,599 discloses a texturizing process wherein the yarn is drawn and heated, and then air jet texturized, and wherein the resulting air textured yarn has low residual shrinkage.
The present invention is based upon the recognition that the problem of the residual shrinkage also exists in air textured yarns which are supplied to the air texturing machine as already substantially fully drawn, fully oriented, thermoplastic yarns. In this regard, a substantially fully drawn yarn may be defined as having an extension at break of between about 7 to 20% and a tensile strength of about 6 to 8 cN/dtex for a technical filament yarn. Such yarn for textile use has an extension at break of between about 20 to 30% and a tensile strength of about 3 to 6 cN/dtex.
It is accordingly an object of the present invention to provide a method and apparatus for producing an air textured yarn, which has a low shrinkage, i.e. a slight residual shrinkage, from a fully oriented, fully drawn, thermoplastic yarn.